Intel 386 User Manual

Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
D-42
D.39 OCW3 (MASTER AND SLAVE)
Operation Command Word 3
OCW3 (master and slave)
(write only)
Expanded Addr:
ISA Addr:
Reset State:
master slave
F020H F0A0H
0020H 00A0H
XXH XXH
7 0
0 ESMM SMM RSEL1 RSEL0 POLL ENRR RDSEL
Bit
Number
Bit
Mnemonic
Function
7 — Clear this bit to guarantee device operation.
6 ESMM Enable Special Mask Mode (ESMM) and Special Mask Mode (SMM):
Use these bits to enable or disable special mask mode.
ESMM SMM
0 0 No action
0 1 No action
1 0 Disable special mask mode
1 1 Enable special mask mode
5SMM
4–3 RSEL1:0 Register Select:
ICW1, OCW2 and OCW3 are accessed through the same addresses.
The states of RSEL1:0 determine which register is accessed. Write 01
to these bits to access OCW3.
RSEL1 RSEL0
0 0 OCW2
0 1 OCW3
1 X ICW1
2 POLL Poll Command:
Set this bit to issue a poll command, thus initiating the polling process.
1 ENRR Enable Register Read Select (ENRR) and Read Register Select
(RDSEL):
These bits select which register is read during the next F020H and
F0A0H (or PC/AT address 0020H, 00A0H) read access.
ENRR RDSEL Register Read on Next Read Pulse
0 0 No action
0 1 No action
1 0 Interrupt Request Register
1 1 In-service Register
0 RDSEL

Intel 386 Specifications

General

Architecture	x86
Clock Speed	12 MHz to 40 MHz
Transistor Count	275, 000
Data Bus Width	32-bit
Address Bus Width	32-bit
Instruction Set	x86
Introduced	1985
Maximum Memory	4 GB
Operating Modes	Real mode, Protected mode, Virtual 8086 mode
MMU	Yes
Voltage	5V
Model	Intel 386
Package	PGA
Process	1.5 μm to 1 μm